Re: [xwiki-devs] [VOTE] [Result] Object properties references (was [proposal][discussion])

Hi devs, On 01/19/2010 03:01 PM, Anca Luca wrote: Actually # is causing problems in velocity too, because it's the macro invocation char. For example, this {{velocity}} #macro(property) this is a test macro #end #set($var1 = "wiki:Space.Page^object#property") $var1 {{/velocity}} displays: wiki:Space.Page^objectthis is a test macro Of course, 6th line can be changed to #set($var1 = "wiki:Space.Page^object\#property") and it will work as expected but the I'd really prefer to avoid escaping, since it's known to be problematic.

Also, Sergiu suggested at some point using the &s, I prefer to avoid that too for as long as possible since it can cause problems with URLs.

Some proposals would be ^ for object names and pipe or semicolon for properties:

wiki:Space.Page^objectName|prop wiki:Space.Page^objectName;prop

or, for property separator, we could also think of ! ~ > or ^ again. In terms of escaping, it means that every time the property separator actually appears in the property name, it has to be escaped and every time the object separator appears in the object name itself, it has to be escaped.

Knowing this, I'd prefer to keep the ^ as the objectname separator since it's quite an unusual char and chances for it to appear in an object name (which we could think of as "as complex as a document name") are small. For property names though, I really wouldn't expect any non alphadigit character (other than _) to ever appear.

Thanks, Anca > a) implementing with indexed references ('multivalued'): > 1 +0.5 , 1 +0, > b) implementing with object names computed as className[number] > 1 +0.5, 1 +1, 1 -1: Vincent, Sergiu, could you reach some sort of an agreement > on this? > > 3/ how to interpret wiki:Space.Page^className (wiki:Space.Page^className#property) > > i) consider invalid > 1 -0, 1 +1 > we can consider always valid with the meaning described at > http://n2.nabble.com/proposal-discussion-Object-properties-references-tp434… > and the approach voted (iii so far, it seems) > > ii) as a list of all objects > not consistent with references model so far > > iii) first object > 1 +0, 1 +0.75, 1 +1 > > iv) object with index 0 > 1 +0 > > Unless there are -1s, I would like to start implementing: > 1/, 2/, a), iii) > > Thanks, > Anca > > > On 01/18/2010 04:54 PM, Anca Luca wrote: >> Hi devs, >> >> to resume, and try to converge to an implementable version, I propose: >> >> 1/ adding only OBJECT and PROPERTY EntityTypes for the moment, referring to an >> object instance and a property instance in a document (a property ref would have >> an object as a parent which would have a document reference as a parent), and >> limiting the implementation to references to properties of object instances >> (leaving aside type definitions ftm). >> >> here's my +1 for this. >> >> 2/ using a serialization of the form >> wiki:Space.Page^className[objectnumber]#property and >> >> a) using indexed ('multivalued') references, adding an additional >> IndexedEntityReference class, to which API caller would have to cast. >> ObjectReference would be such an IndexedEntityReference and provide object >> related helper functions. >> >> b) className[objectnumber] is used as an 'object name', it would be the name of >> the object reference, and it would be the caller of the generic API that would >> have to parse& serialize this kind of strings to actually extract classname and >> object index. However, this would again be all hidden behind the ObjectReference >> API. >> >> I'm 0.5 and 0.5 between the two, any would suit my purpose. >> >> An additional question is what would wiki:Space.Page^className (and >> wiki:Space.Page^className#property) mean: >> i) nothing, we consider it as invalid reference, we'll fix that later, we keep >> it simple ftm >> >> my +1 goes for this >> >> ii) all objects of class className in the document >> >> iii) first object of that class in the document (as >> XWikiDocument#getObject(className) does) >> >> iv) a shortcut for wiki:Space.Page^className[0] (which, note, does not >> necessarily mean the first object in that document, since indexing of objs in a >> document is not recomputed when objects are deleted). >> >> WDYT? >> >> Thanks, >> Anca >> >> On 01/13/2010 02:42 PM, Anca Luca wrote: >>> Hi devs, >>> >>> Short story: >>> 1/ add the CLASS, OBJECT, PROPERTY EntityTypes in the model >>> >>> +1 >>> >>> 2/ serialization for referencing a property of an object >>> a) wiki:Space.Page^className[objectNumber]#property >>> b) wiki:Space.Page^className#objectNumber$property >>> +0.75 for b) >>> >>> Long story: >>> >>> 1/ I would need to extend the EntityReference to be able to target a >>> property in an object in a document. >>> For this, I will need to add >>> >>> /** >>> * Represents a Class Entity >>> */ >>> CLASS, >>> >>> /** >>> * Represents an Object Entity. >>> */ >>> OBJECT, >>> >>> /** >>> * Represents a Property Entity >>> */ >>> PROPERTY, >>> >>> in the EntityType. Although I would prefer an extensible framework that >>> would allow to extend the possible entity types without changing an enum >>> in the platform (for any API user to be able to define its own >>> references), I think this is fairly extensible (these are key concepts >>> in the xwiki model and I don't think they would be changed that soon, >>> and their interpretation is flexible, they could be combined with any >>> parent to generate either references to class definitions or instances). >>> here's my +1 for this. >>> >>> 2/ I would also need a 'standard' string serialization for these. Now, >>> there's also the option to do it in my own module (annotations) because >>> only I need it ftm, but I prefer to have a platform wide approach. Opinions? >>> There are 2 choices, with a potentially different combination of separators: >>> >>> a/ wiki:Space.Page^className[objectNumber]#property >>> >>> pros: it's a suggestive way to access objects by number ([] is the >>> standard syntax for array indexed access and the objects are accessed by >>> index), [] is supported by JCR so maybe we should support it too >>> cons: [] is somewhat inconsistent with all other separators which are >>> just one separator, to the left (right) of the entity, harder to >>> implement the [] separators on the current framework >>> >>> b/ wiki:Space.Page^className#objectNumber$property >>> >>> pros: inline with the separator usage we already have (and easier to >>> implement for this reason), could be easier refactored to contain an >>> object name instead of the number >>> cons: $ separator can collide with velocity syntax (can potentially >>> cause trouble when used in velocity -- an alternative could be the pipe >>> |), could be harder to drop the object number part of the reference to >>> refer a property in a class (if wanted, in the future) >>> >>> I have no other argument between a) and b) but the implementation speed >>> one, so I'd go for a b)-like approach, in the spirit of the current >>> separators. >>> >>> WDYT? >>> >>> Thanks, >>> Anca